The Marcellus shale deposit is an incredible rich and large deposit that straddles many states in the northeastern part of the continent, including areas in Canada. The thick layer ranges from over 900 feet in thickness to just 40 feet. The Marcellus shale layer is located between two thick layers of limestone, so it takes fairly deep wells in order to reach the deposit from the surface. The shale is made of mud that was deposited when the area was covered by an ancient ocean millions of years ago. Over time, the slowly decomposing organic matter found in the mud decayed, forming natural gas which was trapped in the deposit, remaining there to this day.
The Marcellus is found throughout the Allegheny Plateau region of the northern Appalachian Basin of North America. This includes the Southern Tier and Finger Lakes regions of the state of New York, almost all of the northern and western portions of Pennsylvania, eastern Ohio, and western Maryland. Most of West Virginia and the western portion of Virginia are also located over Marcellus shale, and this is where most of the drilling is currently occurring. There is another portion of Marcellus shale in the Delaware River portion of western New Jersey. Another deposit lies straddling the Kentucky and Tennessee borders, and the final major deposit lies below Lake Erie, crossing the border into Canada where it stretches from southern Ontario to Port Stanley.
The most productive region of the Marcellus shale deposit has proven to be in the Delaware River Basin. The Marcellus shale formation underlies about 36% of the Delaware River Basin. This area includes parts of Pennsylvania, New York, New Jersey and Delaware. West Virginia is also heavily underlain by Marcellus shale, which has been a great boost to its economy. States that are over the Marcellus shale have been experiencing an economic boost due to increased demand and drilling natural gas. As the demand for natural gas goes up, so does the price. The price of natural gas today has allowed it to be possible, economically, for natural gas from 'tight shales' such as the Marcellus shale to be recovered.
The area underneath the Chesapeake Bay Watershed holds a rich Marcellus shale formation, as this is part of the Delaware river basin. However, this area must be drilled according to strict guidelines from the Susquehanna River Basin Commission, which oversees the watershed, and the Pennsylvania Department of Environmental Protection. These agencies work to ensure that water is not adversely affected by drilling in the Marcellus formation. If water quality is compromised due to drilling practices, they have the power to and will suspend operations at the natural gas wells.
Extracting natural gas from the Marcellus formation offers many lucrative opportunities for both corporations and states, including a host of jobs. However, in order for companies to be given permits to drill, the actual drilling must occur under conditions that will cause as little environmental impact as possible in order to protect the integrity of the land and the water.